Cavities can spread: why kissing and sharing utensils is riskier than you think

IOL News

4 days ago

But did you know that tooth decay can actually be contagious?
Image: Instagram
When we think about cavities, most of us imagine sugary drinks, skipped brushing sessions, or that stubborn sweet tooth. But did you know that tooth decay can actually be contagious?
Yes, the bacteria behind cavities can spread between people even through something as ordinary (and affectionate) as a kiss.
It sounds surprising, even a little unsettling, but experts say it's a real and common health issue. Let's unpack what this means for everyday life, why it happens, and what you can do to protect your smile and your loved ones' smiles, too.
Tooth decay: it all starts with bacteria
Cavities, also called dental caries, happen when certain bacteria in our mouths break down sugars and produce acid. Over time, this acid eats away at tooth enamel, creating holes.
According to the American Dental Association (ADA), Streptococcus mutans and Lactobacillus bacteria are the main culprits responsible for tooth decay. These bacteria live in dental plaque, thrive in sugary environments, and are the leading culprits in tooth decay.
How do cavities become 'contagious'?
While you can't catch a literal cavity from someone, you can catch the bacteria that cause it. The "Journal of Dental Research" explains: 'Tooth decay is an infectious disease, and the bacteria can spread through saliva.'
That means everyday actions, such as kissing, sharing a fork or spoon, tasting each other's drinks, or even blowing on your baby's food, can all pass these bacteria from one mouth to another.
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Brush twice daily with fluoride toothpaste
Image: Pixabay
This bacterial transfer is most common in families. Research from the Journal of Dental Research shows parents (especially mothers) often pass these cavity-causing bacteria to their children during infancy and toddler years, a process known as 'vertical transmission.'
Will you get sick if you 'catch' these bacteria? Not necessarily, and this is where it gets interesting.
Even if someone transfers Streptococcus mutans to you, whether you get cavities depends on other factors: Your oral hygiene habits (do you brush and floss regularly?)
Your diet (do you snack on sweets and acidic drinks often ?)
Genetics (some people naturally have softer enamel)
Saliva flow (dry mouth makes cavities more likely)
In other words, bacteria start the process, but lifestyle, diet, and daily habits decide the outcome.
Why poor hygiene makes things worse
If you don't brush twice a day and floss, plaque builds up on your teeth. This sticky film is the perfect home for bacteria to multiply.
Once there's a higher concentration of bacteria in your mouth, you're not only at greater risk of tooth decay yourself, but also more likely to pass those bacteria on to others, your partner, kids, or even friends when sharing food.
That's why dentists and health experts stress the importance of maintaining good oral hygiene to protect not just yourself, but the people around you.
Every day, moments can unknowingly spread cavity-causing bacteria.
What are the signs you might have cavities?
At first, cavities might not hurt or show obvious signs. But early clues can include: Brown or black spots on teeth
Small visible holes or 'pits'
Sensitivity to hot, cold, or sweet foods
Pain when biting down
Dentists recommend regular check-ups so cavities can be caught before they get painful.
Why it matters: Cavities are more than cosmetic
Untreated cavities don't just mean fillings or cosmetic concerns. They can lead to serious infections if decay reaches the tooth pulp, sometimes requiring root canals or even tooth removal.
According to the World Health Organisation, the bacteria can also enter the bloodstream, which is a bigger health concern, especially for people with compromised immune systems.
How to protect yourself and others Brush twice daily with fluoride toothpaste.
Floss every day.
Limit sugary snacks and drinks.
Avoid sharing utensils or cleaning a baby's dummy with your mouth.
Stay hydrated, saliva helps wash away acids.
Visit your dentist regularly.